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Commit bf126aee authored by Steven Whitehouse's avatar Steven Whitehouse
Browse files

[GFS2] Patch to fix mmap of stuffed files 



If a stuffed file is mmaped and a page fault is generated at some offset
above the initial page, we need to create a zero page to hang the buffer
heads off before we can unstuff the file. This is a fix for bz #236087

Signed-off-by: default avatarSteven Whitehouse <swhiteho@redhat.com>
parent 476c006b

fs/gfs2/ops_address.c

+14 −3
Original line number Diff line number Diff line
@@ -197,7 +197,19 @@ static int stuffed_readpage(struct gfs2_inode *ip, struct page *page) 
	void *kaddr;

	int error;



	BUG_ON(page->index);

	/*

	 * Due to the order of unstuffing files and ->nopage(), we can be

	 * asked for a zero page in the case of a stuffed file being extended,

	 * so we need to supply one here. It doesn't happen often.

	 */

	if (unlikely(page->index)) {

		kaddr = kmap_atomic(page, KM_USER0);

		memset(kaddr, 0, PAGE_CACHE_SIZE);

		kunmap_atomic(kaddr, KM_USER0);

		flush_dcache_page(page);

		SetPageUptodate(page);

		return 0;

	}



	error = gfs2_meta_inode_buffer(ip, &dibh);

	if (error)
@@ -208,9 +220,8 @@ static int stuffed_readpage(struct gfs2_inode *ip, struct page *page) 
	       ip->i_di.di_size);

	memset(kaddr + ip->i_di.di_size, 0, PAGE_CACHE_SIZE - ip->i_di.di_size);

	kunmap_atomic(kaddr, KM_USER0);



	flush_dcache_page(page);

	brelse(dibh);



	SetPageUptodate(page);



	return 0;